post https://api.themoviedb.org/3/authentication/session/new
You can use this method to create a fully valid session ID once a user has validated the request token. More information about how this works can be found here.
This is step 3 from the How do I generate a session id? guide.
The expected BODY for this request is a JSON object with a request_token field. Example:
{ "request_token": "xxxxxxxxxxxxx" }